Too many patients are getting unnecessary brain scans for headaches, and that use is growing, according to a new study.

Since most headaches are benign, guidelines have recommended against routine MRIs or CT scans. Yet doctors frequently order the expensive scans anyway, researchers say.

"During headache visits, brain scans are ordered an incredible amount of the time," said lead researcher Dr. Brian Callaghan, an assistant professor of neurology at the University of Michigan Health System, in Ann Arbor.

"There are a lot of MRIs and a lot of CTs and that adds up to a lot of money," he pointed out. "It's about $1 billion a year."

Brain scans for headaches jumped from about 5 percent of patient visits in 1995 to nearly 15 percent in 2010, the researchers found.

While brain scans are good for some patients, they are unnecessary for most, Callaghan noted. Scans often find some abnormality, which although benign, could lead to further unnecessary tests and treatment, he explained.

"In 1 to 3 percent of people you will find something on the MRI, whether it be a tumor or blood vessel malformation. You don't want to find something you weren't looking for. It can be anxiety provoking," Callaghan said.

Brain scans can cost as much as $4,000. Insurance, including Medicare, only pays from $500 to $2,000, he said.

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